1. Technical Field
The present invention relates to a prepreg and a resin for preparing the same. More particularly, the present invention relates to a halogen-free prepreg and a halogen-free resin for preparing the same.
2. Description of Related Art
Because technology is progressing continuously, the structure of the circuit board is more and more complicated for different design, different development, or different application of electronic products. The complicated structure of the circuit board, such as multi-layer circuit board, is often used in a printer head, a foldable mobile phone or a portable computer. Usually, the multi-layer circuit board is formed by overlapping several substrates with different features.
The substrate for the circuit board is divided into flexible substrate and rigid substrate. The flexible substrate is made from polyimide (PI), poly(ethylene terephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN) or a material containing rubber resin. The rigid substrate is made from epoxy resin.
Because the material of the flexible substrate and the rigid substrate is different, the prepreg is used to join the two substrates by thermocompression. However, during the thermocompression process, the resin of the prepreg often overflows from the edges of the two substrates and even more serious for manufacturing the circuit boards of the smaller electronic products. Hence, the reliability of the circuit boards is decreased. According to the standard of the Institute for Interconnecting and Packing Electronic Circuits (IPC), IPC-6013 3.3.1.3, the resin overflow from the edges of the substrates should be smaller than 1.5 mm (millimeter) to meet the reliability and manufacturing requirements.
Besides, since environmental consciousness has increased recently, a halogen-free prepreg used as the adhesive interface between circuit boards has become a standard worldwide.